The Changing World of Cat Vaccines

by Nancy Otten, Animal Health Technologist

There are six cat diseases that veterinarians routinely vaccinate for in Canada.  In the past, our cats would make the journey to the veterinarian’s office once per year to receive the injections that protect them from these various diseases.  But things are changing in the world of cat vaccinations.  We no longer vaccinate all cats for all diseases.  Not only that, research has shown that some of the vaccines that we were giving on a yearly basis actually last as long as three years.

Historically, the cat’s annual vaccination protected against Feline Panleukopenia, Feline Viral Rhinotracheitis, Feline Calicivirus, Feline Leukemia, and Chlamydia.  All five vaccinations were combined and administered in one injection.  A separate injection protected the cats against rabies.  Veterinarians are now moving away from this protocol.  Since Chlamydia can be treated with antibiotics, they feel that it is unnecessary to vaccinate against it.  Also, a vaccine has been developed to prevent Feline Immunodeficiency Virus. 

Feline Panleukopenia causes infected cats to suffer from lethargy, anorexia, vomiting, diarrhea, and fever.  The virus is shed in the cat’s feces and is extremely hardy.  This means that the virus can remain viable for months to years without being in a cat’s body.  Therefore it can easily be brought into a healthy cat’s environment from someone’s shoes, hands or clothing.

The symptoms of Feline Viral Rhinotracheitis and Feline Calicivirus resemble those of a common cold (sneezing, runny nose, etc.) but may include high fevers, anorexia, and ulcers of the tongue and cornea.  Once infected, the cats become carriers of the disease for life and may suffer from chronic infections.  Just as in Feline Panleukopenia, these viruses are extremely hardy and can last in the environment for a very long time.  The diseases can be spread directly (a cat sneezing on another cat) or indirectly (a cat sneezing on an object and that object then being brought into contact with another cat.)

Because Feline Panleukopenia, Feline Viral Rhinotracheitis and Feline Calicivirus can be transmitted without direct contact with another cat, all cats, whether indoor or outdoor, should be vaccinated for these diseases.  It has been found that the vaccines used for the prevention of these diseases are effective for at least 3 years.  Therefore the vaccine protocol for these diseases has changed to the following:  8 weeks of age, 12 weeks of age, one year later, and then every three years for the life of the cat.

The Feline Leukemia Virus is one of the most important causes of mortality in cats.  If a cat comes in contact with this disease, it will be feverish and anorexic for a few days and then seemingly recover.   The cat then becomes a carrier for the disease, infecting other cats that it comes in contact with.  It may take years before the disease manifests itself.  In the meantime, the cat passes the disease on to every unvaccinated cat it comes across.  When the cat does eventually succumb, it could develop leukemia (cancer of the white blood cells,) it could develop a lymphosarcoma (cancer that begins in the lymph nodes but can affect many different organs,) or it could develop immunosuppression (the immune system is broken down leaving the cat open to other diseases.) 

Feline Immunodeficiency Virus is the cat version of AIDS and behaves similarly to Feline Leukemia.  After infection, the cats go through a feverish period where their lymph nodes are enlarged; they recover and then shed the virus for months or years before their immune system begins to break down.

Both the Feline Leukemia Virus and the Feline Immunodeficiency Virus are most commonly transmitted through bite wounds from an infected cat.  The virus does not last long in the environment so it cannot be brought into the cat’s environment on clothing, hands, etc.  Because of this, it is recommended that only cats that roam outdoors unsupervised need be vaccinated for the diseases.  These vaccines are only effective for one year therefore the vaccination protocol for these diseases is:  8 weeks of age, 12 weeks of age, one year later, and then yearly for the life of the cat (provided they remain unsupervised outdoor cats.)

The most worrisome disease that we vaccinate cats for is rabies.  It is worrisome not only because it is almost invariably fatal (it causes the brain and spinal cord to swell,) but because it is a disease that can be passed on to humans.  Although the virus is usually transmitted from one animal to another by bite wounds, it is recommended that all cats be vaccinated for it (regardless of whether or not they roam freely outside) because of the potential of human infection.  In British Columbia, the biggest threat for rabies is in bats.  The vaccination protocol for rabies is:  12 weeks of age, a year from then, and then every 3 years for the life of the cat.